haskell-cabal-gild

cabal-gild — format .cabal and cabal.project files

cabal-gild is the formatter for Haskell package descriptions (*.cabal) and project files (cabal.project, cabal.project.local, cabal.project.freeze). It normalises field layout, sorts and de-duplicates build-depends, and can generate module lists from the filesystem via discover pragmas.

Format in place

Run on each cabal/project file you touched:

cabal-gild --io <file>

--io sets input and output to the same path. Format before compiling.

Check without writing

To verify formatting (non-zero exit if it would change the file), e.g. in CI or before committing:

cabal-gild -m check --io <file>

Auto-discovered module lists

cabal-gild can fill in a module list by scanning a directory. Put a pragma directly above the field:

-- cabal-gild: discover src
exposed-modules:

When you add or remove a module, the list is stale until cabal-gild is re-run on the owning .cabal file. Re-running cabal-gild --io <pkg>.cabal refreshes it.

Automatic on save

This plugin installs a PostToolUse hook (scripts/cabal-gild-on-save.sh) that runs on every file write:

• a .cabal / cabal.project* save → that file is cabal-gild-formatted;
• a .hs / .lhs / .hsig save → the nearest enclosing .cabal is re-formatted only if it uses a -- cabal-gild: discover pragma, so discovered module lists stay current.

Manual invocation is therefore mainly for bulk/initial formatting or check mode. After the hook reformats a file, re-read it before editing again.

Companion

Source files (.hs/.lhs/.hsig) are formatted by /haskell-format, not cabal-gild.